|Client:||Water Environment Association of Ontario|
|Location:||Lake Simcoe Watershed|
|Major Outcome:||Demonstrated that non-point source controls are economically and technically achievable.|
Four decades of scientific review and research has identified phosphorus as a key contaminant resulting in significant stress on the Lake Simcoe basin, necessitating a phosphorus reduction strategy to better control and limit the impact of phosphorus loading to the Lake and its ecosystem. The purpose of this study was threefold:
- To review the current design, performance and associated costs of phosphorus removal at each of the 14 STPs discharging to the Lake
- To develop conceptual level designs and order of magnitude costs to achieve enhanced levels of phosphorus removal at these plants; and
- To compare the order of magnitude costs to achieve enhanced levels of phosphorus removal at the 14 STPs in the Lake Simcoe Watershed with the conceptual level costs to achieve reduced phosphorus loadings from rural and urban non-point sources.
The conceptual level upgrades and associated costs to achieve average effluent TP concentrations of 0.10 mg/L and 0.05 mg/L were developed for at all of the STPs discharging to the Lake Simcoe Watershed. These TP load reduction and unit cost per kg TP removed resulting from upgrading the 14 STPs were compared to the projected annual TP loading reductions that could be realized by non-point source controls and the costs of these reductions.
The largest reduction in phosphorus loading to the Lake Simcoe Watershed would be 5,423 kg TP/yr as a result of the upgrade of all of the STPs to achieve 0.05 mg/L TP. This is followed closely by the estimated 5,000 kg TP/yr that would be saved as a result of the implementation of agricultural best management practices (BMPs). The smallest reductions would be achieved by treatment of the Holland Marsh polder water and the upgrade of all of the STPs to achieve 0.10 mg/L at 2,400 kg TP/yr and 2,547 kg TP/yr, respectively. It should be noted that 39 percent of the urban land area was included in the analysis of phosphorus removal in urban runoff. Consequently, the potential exists for further reductions in TP loading from urban runoff.
The upgrade of all of the STPs to achieve 0.05 mg/L TP has the highest cost, followed by the cost to retrofit stormwater systems in existing urban areas. The lowest costs were associated the implementation of agricultural BMP’s and treatment of the Holland Marsh polder water.
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